Air gun pellets have either been designed for deep penetration or for "mushrooming" upon impact The two designs have opposite objectives and have entirely different effects. Pellets designed for deep penetration typically have pointed tips to drive the pellet deeper into the target. Pellets that are designed to mushroom open upon impact typically have a cup-shaped head which spreads open upon impact with the target. Mushrooming defines the deformation radially outwardly and subsequently towards the back of portions of the head of the pellet. Both designs have their advantages and disadvantages with respect to hunting.
Deep penetrating pellets drive further into the body of an animal but do not cause much damage with the result that. unless a vital organ or structure is hit, the animal is not struck down and thus, can escape. Cup headed pellets are designed for mushrooming spread open in the body, but do not penetrate deep enough into the body to damage major organs. They operate on a shock wave principle and may strike down an animal, but not permanently so that again the animal may escape.
It is not desirable when hunting to only wound an animal and permit the wounded animal to escape, since this will not only result in loss of the animal, but will expose it to prolonged suffering. Thus, the effectiveness of both penetrating and mushrooming pellets requires improvement. Hence, the need for a pellet which will not only penetrate deep into the animals body but also cause serious damage to vital organs.